DNC keynoter Castro shows partisan chops

The 37-year old Castro, a rising star in Texas but little known on the national stage, roused the packed audience at the Time Warner Center by claiming that "Mitt Romney, quite simply, doesn't get it."

Castro's tale was in part standard political fare for a party seeking to solidify its standing among immigrant voters.

Castro was raised by a single mother and a grandmother who both emigrated from Mexico, Castro and his identical twin brother Joaquin achieved happiness and success through hard work and a good education made possible by the American dream. But from there, Castro pivoted to an assault on Republican Mitt Romney, whose policies Castro said would "dismantle" the middle class if elected.

"We know that in our free market economy some will prosper more than others. What we don't accept is the idea that some folks won't even get a chance," Castro said. "And the thing is, Mitt Romney and the Republican party are perfectly comfortable with that America."

He added, "I don't think Gov. Romney meant any harm. I think he's a good guy. He just has no idea how good he's had it," ? a pointed jab at Romney's considerable wealth.

Castro also taunted Romney for his shifting positions on issues like abortion rights, gay marriage and his own push for universal health care as governor of Massachusetts.

"Gov. Romney has undergone an extreme makeover, and it isn't pretty," Castro said.

The Romney campaign shot back at Castro's claim the GOP presidential nominee is insensitive to the middle class.

"Middle class families understand that they are not better off than they were four years ago because President Obama's liberal policies have failed to turn around the economy," spokesman Ryan Williams said.

Until now, Castro has enjoyed a spate of favorable media profiles, a landslide re-election last year and speculation about whether he'll become the governor of Texas or even the country's first Hispanic president. His well-received turn at the convention all but guarantees more of such chatter.

Castro was introduced onstage his brother Joaquin, a Texas state legislator from San Antonio now poised to win election to Congress in November

"My family's story isn't special. What's special is the America that makes our story possible," Julian Castro said. "Ours is a nation like no other, a place where great journeys can be made in a single generation. No matter who you are or where you come from, the path is always forward."